1. Field of the Invention
The present invention relates to a substrate for electrical device and methods of manufacturing the same, more particularly, it relates to a substrate for electrical device, which enhancing reliability of electrical devices and downsizing electrical devices.
2. Description of the Related Art
Users of electrical devices are continually demanding better quality of electrical devices, smaller(thinner) electrical devices and inexpensive electrical devices, wherein the better quality of electrical devices includes higher reliability and enhanced heat dissipation of electrical devices. So manufacturers of electrical device research and develop electrical devices for achieving the demands mentioned-above.
At first, referring to FIG. 51 shows a conventional electrical device 100 comprising: a substrate 2 having a through hole 6, a plurality of conductive fingers 3 and a plurality of solder balls 4 thereon, wherein the solder balls 4 electrically connected the substrate 2 to the printed circuit board 7; a chip 5 placed in the through hole 6 of substrate 2; a plurality of conductive wires 8 electrically connected the chip 5 to the conductive fingers 3 respectively; an encapsulant 9 encapsulates the chip 5, substrate 2 and the conductive wires 8, wherein the height “H” of the solder ball 4 is higher than the height “n” of the encapsulant 9 (i.e. the higher the encapsulant 9 is, the bigger the solder ball 4 is needed.). In this manner, more material for manufacturing solder ball 4 is needed, then the cost increased, and the thickness of electrical device is thicker. Moreover, due to the solder ball 4 attaching to the conductive finger 3 by the surface 23 of the solder ball 4 exclusively. It is easy to cause peeling-off problems of solder balls 4 by means of contamination which is happened while operating the attaching (solder balls) process, thermal effects and/or other reasons such as collision. When the peeling-off problem happened, the solder ball 4 separated from the conductive finger 3 easily. It may cause the electrical device 100 to be not functional well.